Begginers Guide to Processing 18650 Cells | Cell Database


Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
hello need some explanation
#1
hello all i need some explantion about cell 18656 battery, im not expert i want to know what is the advantage with this battery ?
if i have lead acide battery 12v 100ah and 12v  100ah cell 18656 battery which is the best and lasts longer thank.
Reply


#2
Pros: abundant, cheap (if getting from recycled material), lots of support, highly flexible to what you want, last longer (even used cells can last longer than lead acid batteries)

12v is 12v and 100aH is 100aH. It doesn't matter the chemistry. They will last equally the same. However, you can't get right at 12v with 18650's as they are a nominal voltage of 3.7V. So when you combine 3 of them in series, you get 11.1V, or if they are in 4s, then you get 14.8V. So your voltage range is a little larger than you'd have with lead acid (LA)

The reason why lithiums (in general, not just 18650's) are catching on in this type of application is because of the versatility, cost effectiveness per size (cost/kWH), and easy of expansion, and the weight. You can have 12kWH of lithiums and will weigh only a fraction of that of LA.
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Dollar Shave Club. Best Razor I've ever used
Certified 18650 Cell Reclamation Technician
Reply
#3
Well said Korishan!
BlueSwordM likes this post
http://www.hbpowerwall.com for a full video diary of my project.... 
https://www.amazon.com/shop/hbpowerwall to buy stuff I use Smile 
Reply
#4
(09-04-2017, 12:15 AM)stiplanet Wrote: ...if i have lead acide battery 12v 100ah and 12v  100ah cell 18656 battery which is the best and lasts longer thank.

Compare Lead Acid and Lithium ion in the table at Battery University: http://batteryuniversity.com/learn/archi...st_battery

If weight is a factor for you, note the first line, Energy Density.
Lead acid is listed as ~30-50 Wh/kg
Li-ion as ~100 to 160 Wh/kg
So, for the same capacity, the weight of lithium batteries is around 1/3 or even less.

Worth noting that most people using Lead Acid will not go beyond 50% DoD (Depth of Discharge) to prolong cycle life, this effectively makes a 100Ah Lead Acid battery equivalent to a 50Ah battery.
Li-ion is a little better with regards to DoD and cycle life, see table 2 here: http://batteryuniversity.com/learn/artic..._batteries
Lead Acid cycle life at 50% DoD is ~400-500 cycles. For Li-Ion at 50% this is somewhere around 1000 cycles (and ~2000 cycles for LiFe)
Where Li-Ion shines is the cycle life versus charge level, see table 4 at the link above.
Reply
#5
Lions are usually capacity rated from full to effective low SoC (usually 4.2V to 3.2V or 2.8V; some datatsheets will show it as low as 2.6V). I'm not sure how the LA's are rated.

Noting that, lions are usually more accurate in their mAh ratings than the LA's. Lions also have a more stable voltage drop. They'll drop from 4.2V to 3.8V under load, and then very slowly drop to 3.2 or 2.8V over the course of the discharge. Whereas the LA's have a tendency to constantly drop voltage during discharge. Think of the lions curve as a lazy sideways S, whereas the LAs is more of a slope. The battery drains faster on a slope than the lazy sideways S (kinda like sky slope where gravity pulls a skier faster on the slope than on a hill)
BlueSwordM likes this post
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Dollar Shave Club. Best Razor I've ever used
Certified 18650 Cell Reclamation Technician
Reply
#6
Many of the Lions are down to 2.5V Smile

Discharge curves of Lithium are rather constant and their SOC can often be calculated based on this. Check this image as example of discharge during different ratings. Note that all cells behave differently so check their datasheet.

Korishan and BlueSwordM like this post
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
#7
Lead Acid (LA): Cheap and robust, but low energy density and heavy, can easily supply very high currents, limited cycle life
Lithium (LI), including 18650s and all other formats: Higher cycle life if used properly, better energy density and weight advantages, somewhat unstable if mistreated, not so good at providing really high currents

LA is suitable for all applications where the operating area is a bit rough, where price is important, but weight and size isn't, and/or really high currents are needed and/or where a "controlled" charge and discharge cannot be provided or a simple charging process is needed

LI is suitable where size and/or weight matters, as well as cycle life, but the current needed is limited (although that scales with size of course, but then again with size and cost as well) and the cells can be operated in a more controlled environment in terms of temperature and controlling the charge/discharge

There isn't one better than the other, that totally depends on what you want to achieve. If your only concern is longest cycle life, then surely go for LI and run them between 3.0 and 4.0V. They will last virtually forever. Depends on your use of course, but you get the idea.

(09-04-2017, 11:07 AM)Korishan Wrote: I'm not sure how the LA's are rated.

Well, that varies a bit depending on manufacturer, manufacturers honesty/transparency, intended use and so on. The same is true for LI though. The topic probably has enough content to write a small article about it, but for now I will try to summarize it.

Generally speaking, it is very similar to how LI cells are rated. A manufacturer of a LI cell will give you a datasheet with discharge curves for certain circumstances and the manufacturer of a LA battery will do the same. However, the discharge rating is given in a different notation. And sometimes there is no datasheet available, just as it is the case with non name branded LI cells.

Let's just have a look at an example. I have a 12V 120Ah LA battery here from a brand called Ective Batteries. This is not a manufacturer, just a brand name that some store made up to sell cheaper, but still very cost effective LA batteries to customers under their own label. The battery is actually made by some kind of OEM. It is a bit of a guess, but I think this is what they are doing. And as a result there is very little info available in this case, there is no datasheet and you only get these three ratings on the battery:

120 Ah (C100)
105 Ah (C20)
90 Ah (C5)

"Cx" means full discharge over x hours. That of course translates to a certain load in amps that is applied to the battery. This is basically the same compared to a LI manufacturer giving you ratings for a "xC" discharge.
Now, there are certain "standards" but no one is forced to use them. Full discharge is usually 1.75V per cell, but anything between 1.60 to 2.00V can be found, depending on the manufacturer. C20 is another standard for rating and comparing LA batteries. If nothing is stated, then it should be a C20 rating. In this case my battery would only be a 105 Ah battery though and therefore they rate it as 120 Ah (C100). Usually you don't even state the C100 rating, you use C3 to C20. A bit shady, but at least they tell you about the C100 rating. You just have to know what it means. And if your application involves a rather slow discharge then this isn't even such a bad thing for you.

Another example I came across recently, because I thought about buying some used ones, is Exide, which of course is a well-known and trusted, high-end manufacturer of LA batteries, with their Sprinter series of batteries. These are made for all kinds of UPS and security-related applications and are probably two or three times as expensive per Ah as the batteries from the first example. The datasheet for these things is probably as extensive as you can imagine. Apart from the usual C3 to C20 they also give you C2 and C1. And also ratings for 3, 5, 10, 15, 20, 30 and 45 minutes (!). And all that for end of discharge voltages from 1.60 to 1.95V in 0.05V increments. And in two flavours, constant current and constant power.

(09-04-2017, 11:07 AM)Korishan Wrote: Noting that, lions are usually more accurate in their mAh ratings than the LA's. Lions also have a more stable voltage drop. They'll drop from 4.2V to 3.8V under load, and then very slowly drop to 3.2 or 2.8V over the course of the discharge. Whereas the LA's have a tendency to constantly drop voltage during discharge.

I wouldn't say that LI is more accurate in their capacity than LA. That totally depends on the manufacturer and isn't really an inherent property of the chemistry.

Same with the voltage drop, that depends. There is an initial and instant drop due to load, and that isn't always to 3.8V for LI, and a continuos drop over time as the cell discharges. It is basically the same for LI and LA. The size of the initial drop scales very nicely with the load. I have the datasheet for the LG HG2 at hand since I'm doing something with them at the moment. The start of discharge voltage for them is between ~4.15 and ~3.3V, depending on the load. A LA battery will do something similar.
BlueSwordM and SimonW like this post
Reply
#8
thank you all for your answers they are accurate and clear to me, now I would like to build a battery of 14v and between 50ah and 100 ah all advice will be welcome to help me start thank you.
BlueSwordM likes this post
Reply
#9
14V is a bit unusual, what do you want to do with that? Usually you go for 12V (or multiples of 12V). That's why you rarely see 3S or 4S LiIon or LiPo batteries as their voltage range for 3S is a bit low and for 4S a bit high to fit the 12V system. With 14V you could go for 4S LiIon (12V empty, 14.8V nominal, 16.8V fully charged) if that fits your needs.

50Ah or 100Ah really doesn't make a huge difference from the construction side of things. If you go 18650 and if we assume a average capacity of 2Ah per cell you would go for 4S25P for 50Ah or 4S50P for 100Ah. If 25P or 50P is enough will depend on the cells you use and your load.

If you know what chemistry and what cell format you want to use (and where you will get them from), then we could go further to building your pack.
Reply
#10
I'm guessing he's thinking of the 4s configuration since 14v / 4 = 3.5V

If you absolutely need 12V (not 13V or higher) to run a device, then just use a buck converter (which is super easy to make; just use a mcu, cap, fet, and pwm to control the fet and you can get any voltage under the input you want; the cap helps to smooth out the ripples from the pulses)

That's my added .02 cents worth
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Dollar Shave Club. Best Razor I've ever used
Certified 18650 Cell Reclamation Technician
Reply


Who read this thread?
72 User(s) read this thread:
jesse.rizzo (09-17-2017, 04:37 PM), willebii (09-04-2017, 03:04 AM), Matt Arklan (09-06-2017, 12:14 AM), hookemdevils22 (09-13-2017, 03:53 PM), sunseeker (09-11-2017, 11:51 PM), SimonW (09-11-2017, 02:46 AM), floydR (09-20-2017, 03:32 AM), NZ55 (09-05-2017, 01:04 AM), Kenny.j (09-05-2017, 04:46 AM), Ivo Staelens (09-11-2017, 05:06 PM), WildCard_25 (09-04-2017, 12:20 PM), Jon (09-11-2017, 03:35 AM), jrandomb (09-05-2017, 10:03 PM), Rad (09-11-2017, 09:20 AM), Geek (09-12-2017, 03:21 AM), iceisfun (09-04-2017, 02:26 PM), kiwi (09-04-2017, 07:44 AM), Rahtid27 (09-05-2017, 12:33 AM), 7Racer56 (09-05-2017, 09:44 AM), dougal (09-15-2017, 08:43 PM), zag2me (09-11-2017, 09:13 PM), Pierre (09-13-2017, 03:25 PM), v850tw (09-08-2017, 02:45 AM), TimFr (09-13-2017, 06:08 AM), N53690 (09-05-2017, 10:03 PM), nautal (09-18-2017, 10:39 PM), barry_mcki (09-11-2017, 05:26 AM), frenchclem17 (09-14-2017, 03:30 PM), Patrick Moreau (09-05-2017, 12:13 AM), karrak (09-11-2017, 05:58 AM), mupp (09-04-2017, 07:14 AM), stiplanet (09-14-2017, 11:48 PM), Ryan Gunner (09-04-2017, 06:58 AM), DarkRaven (09-11-2017, 12:51 PM), Waynevz (09-05-2017, 11:23 AM), paraskevas (09-07-2017, 08:03 PM), netmonk (09-11-2017, 09:39 AM), frnandu (09-11-2017, 05:25 PM), wimpie007 (09-11-2017, 01:57 PM), wim (09-11-2017, 03:20 PM), charlie246 (09-11-2017, 10:26 AM), jdeadman (09-11-2017, 06:12 PM), Mike C (09-11-2017, 07:34 AM), Alec_J (09-04-2017, 02:57 AM), egam (09-04-2017, 12:13 PM), PAF (09-06-2017, 06:34 PM), Korishan (09-17-2017, 10:11 PM), Majorphill (09-12-2017, 01:15 AM), owitte (09-12-2017, 07:09 AM), PaulKennett (09-05-2017, 05:10 AM), mike (09-07-2017, 08:41 PM), daromer (09-11-2017, 12:53 PM), AZ_Tekkie (09-07-2017, 09:22 PM), Jeremy Choy (09-11-2017, 04:57 AM), kktuo (09-08-2017, 06:47 AM), Robert Crawley (09-14-2017, 04:32 AM), Erik Smith (09-05-2017, 01:22 AM), SolarWind (09-08-2017, 01:38 AM), Johnny Stauersbøl (09-07-2017, 08:12 PM), BlueSwordM (09-11-2017, 05:09 PM), Chris Evans (09-12-2017, 12:44 AM), rainbowwarrior38 (09-08-2017, 10:40 AM), Chicken (09-04-2017, 12:32 PM), Stefaan De Ridder (09-11-2017, 05:46 PM), kazbach (09-11-2017, 08:24 PM), silverse2m6 (09-04-2017, 03:45 PM), IronSky (09-04-2017, 12:24 PM), Hanssing (09-11-2017, 06:46 PM), Daggerzz (09-06-2017, 11:38 PM), Dan Lim (09-07-2017, 10:11 PM), watts-on (09-11-2017, 02:06 PM), hbpowerwall (09-04-2017, 05:31 AM)

Forum Jump:


Users browsing this thread: 1 Guest(s)